This invention relates to a self-aligning roller bearing in which a solid lubricant is filled.
A self-aligning roller bearing has a self-aligning function. Namely, its rollers and inner ring can rotate inclined to a certain degree with respect to the axis of the outer ring. Such a self-aligning roller bearing is used in situations where the inner and outer rings tend to incline relative to each other due to mounting error of the shaft to the housing, or deflection of the shaft, and is characterized by its high resistance to vibrations and impact loads.
FIGS. 6A and 6B show a typical self-aligning roller bearing, which comprises an inner ring 21 formed with two raceways 22, an outer ring 23 formed with a spherical raceway 24, and barrel-shaped rollers 25 arranged between the raceways 22 and 24 in two rows. A retainer 26 is provided between the rows of rollers 25 and has fingers 27 protruding into spaces between the adjacent rollers 25 in each row.
The self-aligning roller bearing shown in FIGS. 6A and 6B is used in an environment in which pollution by leaked grease is not permitted. Every space and gap in the bearing is filled with a solid lubricating composition 28. The solid lubricating composition 28 is manufactured by hardening a liquid mixture comprising 5-99 wt % of an ultra-high-molecular-weight polyolefin powder having a particle diameter ranging from 1 to 100 .mu.m and an average molecular weight of 1.times.10.sup.6 to 5.times.10.sup.6, 1-50 wt % of a solid wax containing a low-molecular-weight polyethylene, and 5-99 wt % of a lithium soap-mineral oil grease by retaining the mixture in a dispersed state at a temperature higher than the gelation point of the ultra-high-molecular-weight polyolefin and not exceeding the dropping point of the mineral grease.
One problem with this type of self-aligning roller bearing is that a large torque is produced due to increased sliding frictional resistance resulting from a large number of contact portions of the inner ring, outer ring and rollers is contact with the solid lubricating composition. During high-speed rotation, the interior of the bearing tends to be heated to a temperature above a permissible level due to sliding frictional resistance. This results in sudden deterioration in high-speed rotation characteristics.
An object of this invention is to provide a solid lubrication type self-aligning roller bearing which is low in frictional torque and high in high-speed rotation characteristics.